Point-Of-Care Analysis of Manganese and Lead in Water

Abstract

Metals are ubiquitous in the environment and have long been recognized to pose significant threat to human health. Blood lead (Pb) has been consistently associated with deficits in IQ and academic achievement; manganese (Mn) has been associated with Parkinson’s disease or neurological malfunction in children. Current approaches for determining exposure (e.g., ICP-MS or AAS) require extensive labor, equipment, and long turnaround times. A relatively swift assessment of heavy metal exposure that ultimately reduces costs and turnaround times would benefit pediatric public health nationally and internationally. Our long-term goal is to develop a portable system with disposable sensors to move analysis from the laboratory to the clinical setting. Our sensor is based on electrochemical determination of Mn and Pb, and contains platinum working and auxiliary electrodes, and an electroplated Ag/AgCl reference electrode. An advantage of this sensor is the small size (~10mm on side), the need for only a few drops (~10µL) of sample, and rapid analysis (~10min). We are using cathodic stripping voltammetry for Mn, and anodic stripping voltammetry for Pb. The sensor operational parameters, such as deposition time and potential, supporting electrolyte and pH, were optimized for each metal. The sensor achieved detection limits of 0.9ppb for Mn and 4.4ppb for Pb. We conducted a pilot study to determine Mn and Pb in well drinking water samples from different sites in Marietta, OH (which is home a ferromanganese processing plant). Analyses were performed by diluting samples 2× with pH5.5, 1M acetate buffer, and adding three spikes for the standard addition method. In these samples (n=7), the mean accuracy was 89% with mean precision of 97%, as compared with ICP-MS “gold standard” measurement by a reference lab. Ultimately, the sensor system could act as a simple, fast and low-cost alternative for point-of-care applications in local clinics or resource-limited settings.